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Muriatic Acid and 3% Hydrogen Peroxide First Attempt

Muriatic Acid and 3% Hydrogen Peroxide First Attempt

2014-04-10 by <kbyrne10@...>

I just tried another version of etchant solution. 1. Lowels lumber yard Crown Muriatic Acid and 2. Drug store version of hydrogen peroxide 3 % type.
Mix 1 & 1/2 cup muriatic acid and 3/4 cup hydrogen peroxide in a plastic tupper ware container. My board size was equal to 4 in. times 8 in. Time
around. 30 min. My question is I do not know the strength of the Crown version
of the muriatic acid. Is this time normal and is there a way to speed up the time the board is in the tray?

Re: Muriatic Acid and 3% Hydrogen Peroxide First Attempt

2014-04-10 by <leeleduc@...>

Are you putting the board in the etchant and letting it sit there?. It will take the board a long time to etch this way even if you rock or agitate the tray. When you first put the board into the etchant, you will see the shiny copper turn matte or dull. This (oxide?) layer prevents fresh etchant coming into contact with the copper and slows down the process.

I suggest you place your board copper side up and cover it with 1/4 to 1/2 inch with etchant. Gently and continuously brush the board with a small (2 to 3 inch) foam paint brush. This will brush away the dull layer and expose fresh copper to fresh etchant. This is a cleaner method I came up with after trying Pulsars "Sponge etching" method detailed at http://www.pcbfx.com/main_site/pages/tech_support/no_etching_tank.html

I typically etch a 4 by 6 inch board in a few minutes using Lowes 31% HCL and 3% H2O2 from the supermarket. Make sure your chemicals are fresh. H2O2 can degrade with temperature and time. Higher concentrations of H2O2 will give you a faster etch using this method.

Give it a try.

Re: Muriatic Acid and 3% Hydrogen Peroxide First Attempt

2014-04-10 by <beefyzee@...>

I tried 3% H2O2 once and that was enough for me, nothing happened. The bottle was straight out of the supermarket. Was it degraded ?, I'll never know.

My advice is just go for the "real stuff" and find some much higher % solution. Even if that degrades over time it will still be strong enough. I covered my board with about a 1/4" and just rocked it from side to side, no brushing or rubbing with a sponge. Etched under 2 mins. Fast etching is good etching and reduces undercutting too.

You'll probably find it's cheaper for the actual amount of H2O2 you get to buy it in concentrated form so you win both ways. Remember 3% is 97% water.

Keep it refrigerated and in a light proof container, or wrap the container in silver foil to keep the light out.

Keith.

Re: [Homebrew_PCBs] Muriatic Acid and 3% Hydrogen Peroxide First Attempt

2014-04-11 by Harvey White

On 10 Apr 2014 11:09:00 -0700, you wrote:

>I just tried another version of etchant solution. 1. Lowels lumber yard Crown Muriatic Acid  and 2. Drug store version of hydrogen peroxide 3 % type. Mix 1 & 1/2 cup muriatic acid and 3/4 cup hydrogen peroxide in a plastic tupper ware container. My board size was equal to 4 in. times 8 in. Time 
> around. 30 min. My question is I do not know the strength of the Crown version
> of the muriatic acid. Is this time normal and is there a way to speed up the time the board is in the tray

I think less muriatic acid and more H2O2, say 1 part to 4 parts or 1
part to 3 parts.


Harvey

RE: [Bulk] Re: [Homebrew_PCBs] Muriatic Acid and 3% Hydrogen Peroxide First Attempt

2014-04-11 by Mike Law

Just to chip in my 2 cents:

 

25% HCl (in the UK, maybe ask for "spirits of salt" at the hardware type
shop). 3% peroxide from the chemist. First etch - nice and quick.  All
further etches, not worth bothering with - think overnight!

 

So I went on Ebay and got the food grade 35% H2O2 peroxide.  Outside,
raining, temp not much above 10*C (I was in the garage, so it wasn't raining
on my PCB!).  Threw in H2O2 until it went the lovely emerald green colour.
Chucked in the board, got a stick to swish stuff around, and yeah - like
Dexter's Lab - bubbles, smoking, all very exciting.  

 

For those with bubble tanks, etching many boards, I'd pay attention to
specific gravity and all the fancy sciency bits.  For people like me who
want a board every once in a while: get the acid, throw in some stupidly
strong peroxide and swish it about a bit until it "looks right".  Obviously
it doesn't go green until you've got some copper in there, so don't go made
to begin with.  I like the foam brush idea, I'll try that (or a sponge) next
time.  But don't faff about with 3% peroxide in my opinion, just throw in
something stronger and have fun with the bubbling and smoking! J

 

Mike

 

As an aside, HCl for cleaning stubborn stains from lavatory pans is
excellent.  Throw it on, leave for 20 mins, rinse off. Sparkling loo, zero
effort!
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From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of Harvey White
Sent: 11 April 2014 03:21
To: Homebrew_PCBs@yahoogroups.com
Subject: [Bulk] Re: [Homebrew_PCBs] Muriatic Acid and 3% Hydrogen Peroxide
First Attempt

 

  

On 10 Apr 2014 11:09:00 -0700, you wrote:

>I just tried another version of etchant solution. 1. Lowels lumber yard
Crown Muriatic Acid and 2. Drug store version of hydrogen peroxide 3 % type.
Mix 1 & 1/2 cup muriatic acid and 3/4 cup hydrogen peroxide in a plastic
tupper ware container. My board size was equal to 4 in. times 8 in. Time 
> around. 30 min. My question is I do not know the strength of the Crown
version
> of the muriatic acid. Is this time normal and is there a way to speed up
the time the board is in the tray

I think less muriatic acid and more H2O2, say 1 part to 4 parts or 1
part to 3 parts.

Harvey





[Non-text portions of this message have been removed]

Re: Muriatic Acid and 3% Hydrogen Peroxide First Attempt

2014-04-14 by <soffee83@...>

"H2O2 can degrade with temperature and time."

- I wondered about that shelf life thing, but didn't know if my acid was the one that had gone bad. The past few etches have turned out OK, but seemed to take forever. When I first got attached to that method I was really impressed by how fast it worked and how forgiving it was about conditions and agitation. I remember etching outside in the late fall or winter (I think it was even rainy) and it would burn away so fast that I had to rip it out of the solution after a couple minutes or it would eat through the thinner traces.

I need to get that going again. I'll probably start with all new chemicals and if that doesn't do it, I'll track down the stronger H2O2 you guys are talking about.

George

Re: [Homebrew_PCBs] Re: Muriatic Acid and 3% Hydrogen Peroxide First Attempt

2014-04-14 by Harvey White

On 14 Apr 2014 12:10:34 -0700, you wrote:

>"H2O2 can degrade with temperature and time."
>
>- I wondered about that shelf life thing, but didn't know if my acid was the one that had gone bad. The past few etches have turned out OK, but seemed to take forever. When I first got attached to that method I was really impressed by how fast it worked and how forgiving it was about conditions and agitation. I remember etching outside in the late fall or winter (I think it was even rainy) and it would burn away so fast that I had to rip it out of the solution after a couple minutes or it would eat through the thinner traces. 

That's too fast, you don't get enough control.

The reaction is essentially an oxidization of copper, so the more
oxygen (and warmer the solution) the faster.  

The normal way is to add oxygen by bubbling, your option on using the
H2O2, but you don't want to dilute the solution.

The normal etch time on a board has been mentioned to be about 12
minutes.


>
>I need to get that going again. I'll probably start with all new chemicals and if that doesn't do it, I'll track down the stronger H2O2 you guys are talking about.

All new chemicals will etch faster because of the increased oxygen.
That's why the brushing of the board with a brush works, (as long as
the resist stays on the board, that is).  

Agitation keeps a fresh flow of etchant to the board, one reason why
spray etching works well, as long as it is even.

Harvey

>
>George

Re: Muriatic Acid and 3% Hydrogen Peroxide First Attempt

2014-04-15 by <soffee83@...>

Thanks Harvey,

That time estimate was a slight exaggeration, but it probably wasn't a lot more (maybe 5min or so tops). I'm also usually doing smaller sized boards. Re: the agitation and heat - That was one of the things I really liked when it was working well at first. It seemed to heat itself up, even in cold weather, and bubble and fizz enough where at the most, I might have stirred the top layer around a bit with a plastic knife, but on the small stuff it barely even needed that.

I built a flat vertical plexiglass tank years back, complete with a bubbler and heater, but that was when I was doing ferric chloride (and later, sodium persulfate). It was messy and hard to clean, and I was thankful that the new etchant didn't need all that, but I may start using the bubbler with it and just dropping the tube in by hand.

Thanks for all the tips on the stuff,

George

Re: [Homebrew_PCBs] Re: Muriatic Acid and 3% Hydrogen Peroxide First Attempt

2014-04-15 by Harvey White

On 15 Apr 2014 08:29:03 -0700, you wrote:

>Thanks Harvey,
>
>That time estimate was a slight exaggeration, but it probably wasn't a lot more (maybe 5min or so tops). 

I've had etch times in the 5 to 6 minutes range, but that was bubbling
fresh H2O2 and heating the solution during the summer.  No wonder.
Never was quite so fast.

>I'm also usually doing smaller sized boards. Re: the agitation and heat - That was one of the things I really liked when it was working well at first. It seemed to heat itself up, even in cold weather, and bubble and fizz enough where at the most, I might have stirred the top layer around a bit with a plastic knife, but on the small stuff it barely even needed that.

This is an exothermic reaction, producing heat.  That it bubbles and
fizzes so much says that the reaction is likely going way too fast.

Problem with that is there is a bit of slop time (to a point) the
slower the reaction goes, you'll always undercut to some extent.
Obviously a problem with finer traces, not a problem with 0.1 inch
traces for power supplies.

The evenness of the etch is more important that the etch time, so if
you do bubble etch, you want a good (and uniform) bubble curtain.

>
>I built a flat vertical plexiglass tank years back, complete with a bubbler and heater, but that was when I was doing ferric chloride (and later, sodium persulfate). It was messy and hard to clean, and I was thankful that the new etchant didn't need all that, but I may start using the bubbler with it and just dropping the tube in by hand.

It doesn't absolutely need it, but once it changes to CuCl, then it
will.  No oxygen left for the reaction.

I'd like to do sodium persulfate, but I have no good (inexpensive
read.....) source for it.  Had done Ferric Chloride, and never again,
thanks.

Harvey
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>
>Thanks for all the tips on the stuff,
>
>George